Contact bank for 25-point 10-wiper rotary switches



Nov. 20, 1951 K. w. GRAYBILL ETAL 2,575,306

CONTACT BANK F 25-POINT lO-WIPERROT swnrcn Filed Feb. 16, 1950 2SHEETSSHEET 1 INVENTORS. KENNETH W. GRAYBILL BY HANS SENGEBUSCH ATTORNEY N 1951 K. w. GRAYBILL ETAL 2,575,806

. CONTACT BANK FOR ZS-POINT lO-WIPER ROTARY SWITCH Filed Feb. 16, 1950 2SHEETS-SHEET 2 v INVENTORS. KENNETH W. GRAYBILL HANS SENGEBUSCH ATTORNEYPatented Nov. 20, 1951 CONTACT BANK FOR 25-POINT IO-WIPER ROTARYSWITCHES Kenneth W. Graybill, Elmhurst, and Hans Sengebusch, Villa Park,111., assignors to Automatic Electric Laboratories, Inc., Chicago, 111.,a corporation of Delaware Application February 16, 1950, Serial No.144,521

17 Claims.

This invention relates to switch banks in general and more particularlyto switchbanks for one or two motion switches.

An object of this invention is to provide a contact bank for a one ortwo motion switch which comprises cheaply fabricated parts, easilyassembled and yet accurate and efficient in operation.

In keeping with thi object, a feature of the invention is the novelconstruction of the insulator elements which when assembled into acompleted contact bank hold the metallic contacts stationary and preventall lateral and longitudinal movement thereof.

Another feature of this invention is the provision for slightly bowedcontacts further restricting the possibility of longitudinal contactslippage.

A further feature of the invention resides in the degree ofcompressibility afforded by the insulators.

Still another feature of the invention lies in provision for maintainingclose tolerances in both overall dimension and the distances between thevarious levels of contacts.

These'and other features will be pointed out in the ensuingspecification and appended claims, reference being had to theaccompanying drawings in which:

Fig. 1 is a plan view of an insulator element of the contact bank.

Fig. 2 is a cross section of the insulator element along line AA in Fig.1.

Fig. 3 is a cross section of the insulator element along line BB in Fig.1.

Fig. 4 is a cross section of the insulator element along line CO in Fig.1.

Fig. 5 is a partial plan view of two contact strips as they would bearranged with relation to the insulator element adjacent a perforationfor the compressing means.

Fig. 6 is a partial front view showing a pileup of insulator elements,contact strips, clamping plate and compression means.

Fig. 7 is a cross sectional view of a pileup along line DD in Fig. 5 andevidences a stack of insulator elements, contact strips, clamping platesand compression means and particularly depicts the bowed contact strip.

Contact banks for one or two motion switches have generally been made byclamping together a pileup of insulators with a plurality of metalcontact strips spaced apart therebetween. The

insulators were generally flat, solid and substantially incompressible,necessitating very close production tolerances in order to have thedistance between rows of contacts and overall dimensions of the bankmeet operating requirements. But an even greater trouble factor existsin conventional contact banks, namely slippage of the contacts fromtheir original placed positions, and such slippage is e1ther lateral,longitudinal or both.

The inventors have in thi invention provided. a molded, shaped insulatorelement. Because of relatively small area raised edges on theinsulators, there is a sufficient degree of compressibility tofacilitate maintaining close tolerances for both overall dimensions ofthe contact bank assembly as well as distances between the variouslevels of contacts therein.

The invention further provides in the form of the insulators means toslightly bow the contact strips upon compression of the bank assembly aswell as seats and shoulders for the contact strips to engage so as toeliminate all possibility of slippage, either laterally orlongitudinally. A notch in the contact itself to engage an insulatorshoulder lends itself even further to this end.

Having generally described our invention, now, with reference to figuresand numbered components we shall describe the invention in greaterdetail.

Referring again to the structure illustrated in Figs. 1-7 inclusive, thecontact bank consists of metallic contact strips l, molded insulatorelements 2, clamping plate 3 and compression means 4.

The insulator elements 2 are molded so that all edges, upper and lowerwill be raised. The upper raised edges right and left will themselvesalternately have shoulders 5 and depressions 6. The lower raised edgesright and left likewise alternately have elongations l and recesses 8.Shoulders '5 will all be immediately above lower recesses 8 and lowerelongations i will all be immediately below depressions 6. All shoulders5, right and left are in line longitudinally and similarly alldepressions right and left, lower elongations right and left andrecesses right and left. will be longitudinally aligned respectively.Upper depressions S are of a depth equal to the sum of the thickness ofa contact strip l plus the depth of a lower elongation l. The uppershoulders 5 are in height equal to the depth of adjacent depressions 6,and likewise, lower elongation I are equal in length to the length ofadjoining recesses 8. Longitudinally betweencorresponding pairs of lowerelongations I, right and left, is a semi-cylindrical appendage 9 whichwill be slightly greater in height than one elongation of its alignedpair of lower elongations, substantially equal to the other and equal inwidth to both. As shown in Fig. '7, the semi-cylindrical appendage 9cooperates with the depressions 6 and elongations jl to causecontactstrip l to-bow beneath the appendage 9. Right depression His-"lower thanleft depression 6 for the purpose of produc ing nearly all of thedisplacement caused by the bowing of strip l at the terminal end. of,contact strip I, while the contact end'of the striprernainssubstantially horizontal. As shown further in Fig. 7, and also in Figs.2, 3 and 4, right elonga-' tion 1 is longer than left elongation F, forthe purpose of fitting into the corresponding depres sions 6 to give afirm interlocking relationship between adjacent supports and maintainthe proper bow in the contact strips. Longitudinally betweencorresponding pairs of upper shoulders right andfileft, are raised ringslilintegral with the insulator element's, and Which are reinforcem tsforperforations or bores l l extending thru s raised rings I8- and theinsulator elements. T esebor'es orperforations are for acceptingsuitablecompression means when a group of such like insulator elementsare stacked ina pileup.

' These insulator elementsmay be molded from any plastic or syntheticresin material such as a phenolcondensate product and in a particularThe dye alPsha-peof the insulator element will depe upon the type switchto which it is to be adapted; For standard Strowger type switch rotaryswitch banks, the plan shape may be a semi-circular one as shown in Fig.1,

with pairs of corresponding components such as upper-depressions foreand aft arranged radially eon: However, the inventors do not wish to limtheir invention to a semi-circular bank as it;is equally adaptable to arectangular type arrangement" with the depressions fore and aftsuitablegeometric form.

C lonta'ctfstrips'l are then laid longitudinally equally spaced apart;or' for that matter, to any in 'aligned; pairs of upper edgedepressions6.

The cfo aetjstrips' may'be'cut' or stamped from "any" suitableconducting material, preferably brass or Rhosphorbronze. The strips as"shown injFig Sli a e anjoVeralI wedgeshape for use in aj' spaced apart"arrangement. Their oful d" justas readily'be rectangular for use ina"parallel' spaced apart arrangement.

This seating in depressions 5, assumes a fixed positi "forfthecontact's'withoutlateral move- Alo'ngorie lateral edge of each 'strip'l'is cut an obtuse isoscel'es angle l2 whose vertex e" at the center'point' both laterally; and lon tudinally'of the strip; Thisl'arg'eangular "positioned so that the contact may circumvent the compressionmeans passing mm b'or bodiment in Fig. 5. Notch [2' may be forward or'rearward' of the angular cut previously described as the circumstanceswarrant. Fig. 5

with the exception that lower appendages fi are 55. compressibility ofthe" relatively small" area depressions andff protrud 3 shows oneembodiment with notch 13 rearward of cut l2. This notch 13 engages ashoulder 5 and thereby prevents longitudinal movement of the contactstrip. A further purpose of notch I3 is that when it is cut at apredetermined position, it will. insure; the uniform protruding lengthof' all contacts in the "bank. Forward ends I4 and rearward ends I5 ofcontact strips I protrude beyond the bank in well known manner, and.said, ends are not of unfamiliar design i'nthelart.

'Toform now a contact bank or pileup, it is only. necessary topile up apredetermined number 'of insulajtQr elements 2 equipped with contact,strips l as hereinbefore described, one upon another until the desirednumber of rows is reached; The.v uppermost insulator element It is thenadded but without contact strips in its.

upper depressions. At, this stage, all lower elongations l neatlydovetail into upper depressions 6; with appendages 9 lightly restingcentrally or perforations aligned with those in the insulator elements.

' The bottom of this pileup is then fitted into a bottom insulatorelement [1, shown in Fig. 7, which for all practical purposes isidentical to the insulatorelements 2 described hereinbefore not present,and the lower raised edges maybe ionge'r; In the embodiment shownin Fig;'7, bottom insulator Il is shown to have somewhat longer-lower edges [8.

Beneath the-bottom insulator II- is placed-another clamping member3"described her'eihbefore.

- Application of compression means 4; willnow complete theflbank. Allelongations T dovetail tightly into depressions 6, snugly hoIding'contact strips I while appendages 'Q'being slightly greater in" depththan 'th'e lower elongations' 'l press down centrally on allcontactstrips-"eats ing them to flex or bow'slightly. I

In this position the contact bank: is complete.

' Notches" l3 co-ioperatihg wi-th shoulders? along with the bows in'thecontac't strips"; due tofthe action of the compression means i -andappendag'e's- 9 upon strips" I hold strips-l fixed and' withoutlongitudinal motion while; the se ting; arrangement providedfonthejcontact s'tr'ip's'j I by depression 6 willhold saidstrips freefroin lateral mbtiofi. 1 z An additional factor to be notedis thesli'ghtraised edges of insulator elements 2; which allow for mai taining.close; tolerances bo thf for 'overall d n ion ii zbont t nki 's, wdistances between the varioq levelsfor- Ha i des r b d t ,7 n f io i' 31What we claimand desi e to" be; protectedby: is 'uance of LettersPatent'of th'e UnitedStatesisi 1. In a switch bank aplulifalityiofnioldeiinsulato'r elements o upon anojth 'ergrais' d-"'edges on said insulator elements, "upp. llf raised eidgs t. n e y sal emav. he ldr i i depressions respectively alj ned nf pa rs; lowerraisededges right and left having alternately elongations' and 'Irecessions respe uy ly; aligned in pairs, 's'aid' elong' atifolnsin'irned iately below depressions; contact s ipsJaying ins'ai'"th'erebeyon l n itior'is Fw li i ei li lanexticswer'insuiatcreiemefitandsaiurecessitns on said lower raisededges receiving said shoulders of said next lower supports, and means tocom- .press said elements, said shoulders, depressions,

recessions, elongations and raised edges being so constructed as to holdsaid contact strips firmly in place and said insulators together underthe compression of said means.

2. In a switch bank as claimed in claim 1,

semi-cylindrical appendages longitudinally between said lower edgeelongations, the depth of said appendages being slightly greater thanone of said elongations and substantially equal to the other, saidappendages co-operating with said means to bow said contact stripsimmediately thereunder upon application of said means.

3. In a switch bank as claimed in claim 1, said insulator elementshaving a plurality of aligned perforations between said contact strips,said perforations to accept said compression means.

4. In a switch bank substantially as claimed in claim 1, said insulatorstrips comprising a molded synthetic resin.

, 5. In a switch bank substantially as claimed in claim 1, saidinsulator strips comprising molded polymerized ethylene.

6. In a switch bank, a plurality of contact strips, a plurality ofsemi-circular insulator ele- ,ments, raised edges on said insulatorelements,

each of said insulator elements comprising a plurality of radially equalintegral components; every other radial component having its lower edgeselongated fore and aft and a semi-cylindrical appendage longitudinallytherebetween of slightly greater depth than on of said elongated loweredges and substantially equal to the other, While the upper edges rightand left immediately thereabove are depressed, the depth of saiddepression being the thickness of a contact strip plus the depth of alower edge elongation; and therebetween every other radial componenthaving shouldered upper edges right and left and recessed lower edgesright and left; a contact strip laying in each pair of upper depressionsright and left and projecting thereloeyond, in-

sulator elements so equipped with contact strips stacked one aboveanother in a pileup, elongated edges fitting into depressions; andcompression means to hold said strips and insulator elements together,said depressions and said compression means co-operating with saidsemi-cylindrical appendages and raised edges to cause a bow in saidcontact strips and fixedly hold them in place.

7. In a switch bank as claimed in claim 6, said bowed contact stripscomprising equal lengths of metal, one lateral edge thereof having twoindentations, one indentation being obtusely angular in shape, thevertex of which is the longitudinal and lateral center point of saidcontact strip, the other indentation being a rectangular notch rearwardof said first indentation, said one indentation functioning tocircumvent said compression means, said other notchlike indentationengaging an upper aft raised edge portion co-operating with saidcompression means to fixedly hold said contact strips in place.

8. In a switch bank, a plurality of bowed contact strips, a plurality ofmolded semi-circular insulator elements, raised edges on said insulatorelements, the upper right and left raised edges of said insulatorelements having alternate depressions and shoulders therein, said bowedcontact strips laying in corresponding pairs of depressions right andleft, and the lower right and left raised edges of said insulatorelements alternately elongated and recessed, elongations of lower edgesimmediately beneath depressions in upper edges, and longitudinallybetween said lower edge elongations semi-cylindrical appendages slightlygreater in depth than one of said lower edge elongations andsubstantially equal to the other; a predetermined number of suchinsulator elements with contact strips stacked one upon another in apileup, lower edge elongations of the next higher fitting into upperedge depressions of the next lower, the uppermost insulator elementbeing deprived of said contact strips, semicircular clamping platesabove and below said pileup, and compression means to verticallycompress said pileup, said means co-operating with said semi-cylindricalappendages resting centrally on the next lower contact strip, andfurther co-operating with the dovetailing of said elongations intocorresponding depressions so as to cause said contact strips to bow andsaid elongations and depressions to mesh holding all constituentsfixedly in place.

9. In a switch bank, a plurality of insulator supports arranged inlayers, a plurality of contact strips in spaced apart relationshipbetween said layers, compression means in said bank to verticallycompress said layers, and means integral with said insulator supportsfor causing said strips to deflect upon application of said compressionmeans to cooperate with said supports to rigidly fix said strips inposition in said bank.

10. In a switch bank, a plurality of semicircular insulator supportsarranged in layers, a plurality of contact strips in a radial spacedapart relationship between said layers, compression means in said bankto vertically compress said layers, and means integral with saidinsulator supports for causing said strips to deflect upon applicationof said-compression means to cooperate with said supports to rigidly fixsaid strips in position in said bank.

11. In a switch bank, a plurality of insulator supports arranged oneupon the other having apertures therein, a plurality of fiat contactstrips arranged in a spaced apart relationship between each of saidinsulator supports and projecting transversely through said supportsthrough said apertures, compression means in said bank for verticallycompressing said supports one upon the other to hold said strips in saidapertures, and means integral with said support for causing said stripsto bow upon application of said compression means.

12. In a switch bank, a plurality of formed insulator supports, havingprojections and recesses thereon, arranged in a stratified manner, theprojections of one of said supports partly engaging correspondingrecesses in a support in the next stratum, contact strips passingtransversely through said recesses in said supports and extendingtherebeyond, central projections in said supports transversely alignedwith the recesses in the support in said next stratum, and compressionmeans in said bank for vertically compressing said stratifiedarrangement to cause said central projections to deflect said strip andto cooperate with said partial engagement to fix position of said stripin said bank.

13. In a switch bank, a plurality of contact strips arranged in rows ina spaced apart relationship, insulator supports separating said rows, aplurality of downward projections on opposing sides of said supportstransversely aligned, said supports also having a plurality of recesseson spac ous verse alignment with saiddownward projections and locatedtherebetween, said central downward projections having adepthgreaterthan one of said downward projectionsand substantially equal tothe other, compression means to compress said supports vertically tocause said projections and recesses to firmly gripsaid: strips toprevent lateral movement; thereof, and: to cause said central: downwardprojections todeflect saidstrips to cooperate with said: projection andrecesses to prevent longitudinal movement of saidstrips thereof.

I4. Ina switch bank, a plurality of insulator supports arranged: inlayers, a plurality of contacts str-i-ps arranged in a-spaced apartrelationship" between said layers, means integral with said supports forpreventing lateral movement of said strips insaid support, meansintegral with said strips for interlockingwith said.- integral supportmeans to prevent longitudinal movement or said strips in said support,compression means tovertically compress said layers, and, other meansintegral with said supports for causing saidstrips to deflect uponapplication of said compression means to further prevent longitudinalmovement thereofl' 15; In a switchv bank, a plurality of insulatorsupports arranged in layers, a plurality ofcontact strips arranged in aspaced apart relationship-betweensaid layers, means integral with-saidsupports for preventing: lateral movement of said stripsbetween saidlayers; notches in said strips interlocking with said. means forpreventinglongitudina-lmovement of said strips between said layers,compressionmeans to compress said layers vertically upon saidv strips,and other means integral. with said supports for bowing said stripsuponapplication or said compression means to further preventlongitudinal movement thereof.

1 6'. In a'switch bank, a plurality of insulator supportsarrangedinlayers, raised edgeson the uppensurtaces or said supports, dependingedges on the lower surfaces of said supports; said edges havingalternately-spaced shoulders, the shoulder of the upper edgeofiset' fromthe shoulderon the lower edge thereof, contact strips between saidsupport layers, said contact strips resting between said raised edgeshoulders and; overhanging said supports, said depending edgeshoulderofa higher support also resting between said. raised edgeshoulders of. the next lower support directly over said contact strips,compression means to vertically compress said. layers to retain said.strips fixed. between said shoulders, at central; depending: projectionfrom said lower'surface, said central depending: projection bowing. saidcontact strip upon application of said compression means to furtherretain said: strips? between said shoulders;

17-. In a, switch. bank; a plurality; of insulator supports arrangedlayers,v raised: edges on; the upper surface of said supports, shoulderson! said raised edges, depending edges on the lower surfaceof saidsupports-, shoulders on. said depending edges said shoulders on saidupper edges transversely aligned in pairs, said shoulders. on saidloweredges also aligned in pairs, said lower edge shoulders vertically"ofiset from said upper edge shoulders so that said; layers. of supportsi-ntermesh, a plurality of: contact strips resting between; said upperedge shoulders and enclosed by saidintermeshing of. said layers,rectangular notches. in. said cont-act strips, said. notches engagingsaid raised edge shoulders to prevent longitudinal movement of; saidstrip: through said supports, a central depending projection on thelower surface of said: supports of greater length than one ofsaid:depending edge. shoulders and substantiallyequalto. the. other, centraldependent projection. laterally offset from said depending edgeshoulders, and compression. means for compressingisaid layersvertically, said depending. central: projection flexing said: contactstrip. to further prevent longitudinal; movement thereof uponapplication of: said means.

KENNETH W. GRAYBZ'LL. HANS SENGEBUSCH.

EEFEF ENC S. siren,

The following references are ofrecord in the file of this patent:

UNITED STATES. PA'I'ENTS Number Name Date; 7

1,903,392 Triifany Nov; 14,.191 1 13499;137; Len'aghan Mar: r922 2; 4 57,! 703- Merkel Dec. 28, 1948

